A unique feature of the S2 library is that unlike traditional
geographic information systems, which represent data as flat
two-dimensional projections (similar to an atlas), the S2
library represents all data on a three-dimensional sphere
(similar to a globe). This makes it possible to build a worldwide
geographic database with no seams or singularities, using a
single coordinate system, and with low distortion everywhere
compared to the true shape of the Earth. While the Earth is
not quite spherical, it is much closer to being a sphere
than it is to being flat!

S2 Features

Notable features of the library include:

Flexible support for spatial indexing, including the ability
to approximate arbitrary regions as collections of discrete
S2 cells. This feature makes it easy to build large distributed
spatial indexes.